This implementation memo applies to any cleanup site where vapor intrusion is a potential concern. In 2009, the Washington State Department of Ecology published draft vapor intrusion guidance, publication no. 09-09-047. This memo answers frequently asked questions about that guidance. Many of the questions are about technical or policy changes that have happened since we published the draft guidance in 2009.

REVISION NOTE: This memo was originally published as a review draft on June 22, 2018. In November 2018, we finalized it based on comments received during the draft memo’s public comment period July 5 through August 10, 2018.

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The mission of the Department of Ecology is to protect, preserve, and enhance Washington’s environment. To help us meet that goal, please consider the environment before you print or request a copy.

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